Experts have warned the UK is losing the battle to eradicate giant hogweed, an invasive species described as the country’s most dangerous plant.

Despite longstanding efforts to eradicate the pernicious “beast”, it has gained a foothold across the nation, with horticulturists cautioning that recent flooding and warm weather may have aided its proliferation.

Originally hailing from the Caucuses, the carrot family member is thought to have been first introduced to Britain in 1817, when Heracleum giganteum seeds were sent from Russia to Kew Gardens.

While initially favoured in ornamental gardens due to its pleasant appearance and impressive stature – reaching heights of more than five metres (16 feet) – it has been illegal to grow the plant in gardens for decades now, as a result of it being highly toxic.

Its poisonous sap causes sunlight-sensitive burns and blisters, which can scar for years, and can induce blindness if contact is made with the eyes – leading Mike Duddy of the Mersey Rivers Trust to dub it ”the most dangerous plant in Britain”.

While it typically appears along waterways, experts warn it is also springing up in gardens and on verges. Plant Tracker reports hundreds of sightings across all four UK nations, as far afield as Inverness, Pembrokeshire, County Londonderry and Kent.

The plant – which is easily confused with benevolent cow parsley – thrives in warm weather, and chief horticulturist at the Royal Horticultural Society warns recent flooding may have carried seeds downstream to new locations.

“The beast has purple blotches and coarse hairs on its stems,” Guy Barter told The Times. “In most places where you see it in summer, it is enormous. It’s a very pretty plant but I would strongly advise anyone not to grow it. It can cause some very nasty injuries which take a long time to heal.”

Mr Duddy of the Mersey Rivers Trust also told the paper: “Co-ordinated action is the only way to get rid of it. In the 1990s there was very little of it. The proliferation has got worse every year.”

He told The Independent that other factors in its continued spread are the lack of financial resources devoted to its control, the lack of knowledge about its life cycle, and “a sense of inevitability among local authorities that the plant, once established, can not be controlled”.

Local authorities can use the Wildlife and Countryside Act 1981 and the “much better” Police Crime and Anti Social Behaviour Act 2014 to enforce control of the weed.

But Mr Duddy said that he believed they largely do not do so because “the majority of them do not have the plant under control on their own land, because it costs them money to enforce the law and because no one in most local authorities want to take responsibility for it”.

However, he remained hopeful that the plant’s prevalence could be “massively reduced” were the available control methods to be funded and acted upon.

Parents in particular are warned to ensure their children are educated about the dangerous plant.

In 2015, at least five children were left with severe burns after coming into contact with the plant in parks in Greater Manchester.

At the time, the mother of one seven-year-old girl who was hospitalised with her injuries said that she initially believed her daughter’s injuries were due to a bramble scratch.

“[Two days later] they’d turned into blisters, by that point she’d also got a high temperature and was in significant pain,” Annie Challinor told the Daily Mail. “She was very upset by the blisters, they looked hot and angry, and she cried a lot.”

She added that hospital staff had told them their daughter would “be left with a permanent scar and that bit of skin will re-blister every time it is exposed to sunlight, so it’s total sunblock for life on that bit of skin”.

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